Bedford-type palladacycle-catalyzed miyaura borylation of aryl halides with tetrahydroxydiboron in water
A mild aqueous protocol for palladium catalyzed Miyaura borylation of aryl iodides, aryl bromides and aryl chlorides with tetrahydroxydiboron (BBA) as a borylating agent is developed. The developed methodology requires low catalyst loading of Bedford-type palladacycle catalyst (0.05 mol %) and works best under mild reaction conditions at 40 °C in short time of 6 h in water. In addition, our studies show that for Miyaura borylation using BBA in aqueous condition, maintaining a neutral reaction pH is very important for reproducibility and higher yields of corresponding borylated products. Moreover, our protocol is applicable for a broad range of aryl halides, corresponding borylated products are obtained in excellent yields up to 93% with 29 examples demonstrating its broad utility and functional group tolerance.
The invention relates to processes for the synthesis of aryl or alkene borates which comprises reacting: (i) an olefinic compound having a halogen or halogen-like substituent in a vinylic substitution position, or (ii) an aromatic ring having a halogen or halogen-like substituent in a ring substitution position, with a disubstituted monohydroborane in the presence of a Group 8-11 metal catalyst. The invention also relates to the use of these borates in coupling reactions. The invention further relates to certain disubstituted monohydroboranes and aryl or alkene borates.
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(2010/02/05)
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